Is there anyone can tell me some symptoms of "decayed tooth" in English?

Is there anyone can tell me some symptoms of "decayed tooth" in English?

Tooth decay usually does not cause symptoms in its early stages. Toothache, the most common symptom of tooth decay that has been present for a long time, is caused by infection or irritation of the pulp. The pain may become worse when you:

Eat sweets.
Eat hot or cold foods or drink hot, cold, or acid-containing liquids, such as citrus drinks.
Chew food or gum.
Breathe in cold air.
Brush your teeth.
Other common symptoms of tooth decay include:

Bad breath or a foul taste in the mouth.
White, gray, brown, or black spots on the teeth.
Loose fillings.
A broken tooth or a tooth that is sensitive to pressure.

Ask your dentist directly if the tooth is decayed, that's all. (Your question is quite misleading as you said your tooth was decayed but you didn't know.....i don't now how to help you except this)

I only can say that the color of the decayed tooth is differ from others. It maybe brown(or black), and also there maybe hole on the said tooth.
Sorry, i do not know others abt it.

The tooth which is decaying hearts very much, and I can feel some small hole on the top of the tooth when touching it with my tongue.

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good luck

I only can say that the color of the decayed tooth is differ from others. It maybe brown(or black), and also there maybe hole on the said tooth.
Sorry, i do not know others abt it.